Print a better error when attempting to use token based authentication and service account credentials at the same time

The agent support both basic token authentication and a service account credentials file.

Right now the token can be specified in either the config file or the `--auth-token` flag.

The execution should fail with a clear message if a service account credentials file is provided but there is a basic authentication token specified as well.

追蹤設定檔和 --auth-token 旗標的載入方式，然後找出接受服務帳戶憑證的位置。使用憑證檔案和權杖重現一次執行，並確認執行會因一個清楚說明兩種驗證方法不能同時使用的錯誤而停止。

由索引模型根據 Issue 內容生成。